1. Field of the Invention
The present general inventive concept relates to an electro-photographic printer, and more particularly, to an electro-photographic printer having a foreign substance prevention unit, which prevents foreign substances from accidentally going into a waste toner transfer unit of the electro-photographic printer via a waste toner injection hole.
2. Description of the Related Art
In general, an image forming apparatus forms an image on a piece of paper by forming a latent electrostatic image on a photosensitive medium using a light scanning device, transferring the latent electrostatic image onto a printing medium using toner particles to form a toner image, and fusing the toner image onto the printing medium.
Such an image forming apparatus obtains a desired image by transferring a toner image onto the printing medium using a potential difference between the photosensitive medium and an image transfer unit. However, the toner image is not completely transferred from the photosensitive medium to the image transfer unit or from the image transfer unit onto the printing medium, thus leaving some of the toner particles used to form the toner image behind on the photosensitive medium or in the image transfer unit. This residual toner is called waste toner. The waste toner is removed from the photosensitive medium or the image transfer unit by using a cleaning apparatus and then stored in a waste toner container.
FIG. 1 is a side view of a cleaning apparatus 11 and a waste toner injection hole 31 of a conventional electro-photographic printer, and FIG. 2 is a perspective view of the waste toner injection hole 31 of FIG. 1.
Referring to FIGS. 1 and 2, the cleaning apparatus 11 is installed at one side of a photosensitive medium 10 and removes toner residues (waste toner) from a surface of the photosensitive medium 10. The photosensitive medium 10 and the cleaning apparatus 11 can be assembled into one device, which can be installed in or separated from a main body of the conventional electro-photographic printer. When installed in the main body of the conventional elector-photographic printer together with the photosensitive medium 10, the cleaning apparatus 11 is connected to a duct 30 through a waste toner injection hole 31 of a duct 30, which is installed in the main body of the conventional electro-photographic printer. Accordingly, the waste toner removed from the surface of the photosensitive medium 10 by the cleaning apparatus is injected into the waste toner injection hole 31. In FIGS. 1 and 2, reference numeral 20 denotes a bracket installed in the main body of the conventional electro-photographic printer.
When the device, into which the photosensitive medium 10 and the cleaning apparatus 11 are assembled, is separated from the main body of the conventional electro-photographic printer, the waste toner injection hole 31 is exposed to an outside of the printer 30, so that foreign substances may accidentally go into the duct 30 via the waste toner injection hole 31 due to a user's carelessness.
A transfer unit (not shown) is provided in the duct 30 for efficiently transferring the waste toner, which is injected into the duct 30 via the waste toner injection hole 31. Accordingly, if the foreign substances go into the duct 30 via the waste toner injection hole 31, it may adversely affect an operation of the transfer unit, thereby hindering the transfer unit in smoothly transferring the waste toner injected into the duct 30.
The above-described problem may cause a malfunction of the conventional electro-photographic printer, which requires an entire waste toner transfer unit of the conventional electro-photographic printer to be replaced with a new one or requires the conventional electro-photographic printer to be taken apart and then fixed. Therefore, it is necessary to develop an apparatus for preventing the foreign substances from accidentally going into the duct 30 via the waste toner injection hole 31.